def. 1 - when you have alcoholic drunk and you needed one. and you feel like your whistle is wet after.
def. 2 - buttering somebody up
ex. 1 def. 1 - you had the shakes all day until you went to the liquor store got home and wet your whistle
ex. 2 def. 2 - i knew you weren't going to give me the job until i wet your whistle